Is it too late to "tame" my sebrights?

They're only young, but no matter how old they are, all animals can be tamed to some degree, which is a degree of their choosing and partly based on both their character and yours. Chickens are nowhere near as stupid as we've been taught. They're one of the few animals proven to learn compassion and able to learn from watching. Everything you do with your chooks, all the others are observing and learning from. Even having one chicken trust you buys you some credibility with the others, well, except the most suspicious, human-averse or traumatized ones, anyway.

The right person combined with the right animal and the right communications can result in a tame anything, even when the animal remains effectively perfectly wild in all other respects and possibly wild as far as all other humans are concerned. It's a sort of implicit agreement, a development of trust, not just a concerted attack on flight/fight instincts until apathy ensues.

You need to be aware of your body language as much as theirs. It's easy to send the wrong signals, and what is ok or not ok varies according to the animal, so you have to observe their reactions to you for the clearest communications.

Sometimes it can be as simple as stopping walking and turning your body slightly off-angle to a chook when you see it start hurrying away from you. Talking to them helps a huge amount. Having treats to throw, to help positively reinforce a break from the flight reaction, can also help alter behavior patterns.

Ironically, the roos can be one of the easiest ways to help tame skittish hens. The roos already have the hen's trust; when a roo says 'here's food', unless he's a serial liar, the hens will come. If he looks at you and makes the predator alarm or be alert call, even when you've taken steps to earn his trust, well, then he's best gone.

Hand-feeding roosters can help encourage hens to come to and trust you; some of my roosters could bring any skittish and wild hen running straight to my feet, because the hen trusted him and the rooster showed her he trusted me. This worked like a charm even with traumatized hens who had been absolutely terrified of humans before. But treats will do that anyway, though it can take years. Some hens will take a lifetime to tame, just going by treats alone.

I'd spend time in their pen, just reading or whatever, or observing, getting them used to my presence, talking to them, sometimes moving around and doing things that don't involve chasing or cornering them, so they get used to my movements without freaking out about them... Talking is very important, you can 'talk' most animals into trusting you. Tone of voice is a universal language, you don't need any education on a species to hear its anger when it makes a sound of threat at you.

Being the sole source of great treats is also helpful, as is slowly reeling them in rather than trying to force it all at once. Spend time getting them to choose to approach you, is what I mean. Trust is what you need.

It helps to always talk to them when offering them food, and keep talking for a bit as they eat, saying something repetitive, distinctive, and simple, which can be repeated at volume to call them home, so this way they will come when called. I just say 'here, chook-chook-chook' --- kind of sounds like their own food call, and when you're throwing down food or repeatedly pointing at it, they get the idea real quick. Using this food call I can bring them running and flying back into the coops in the middle of the day if necessary, even when they were foraging off in the forest and fields.

Some of them may be human-averse, some animals just are, and there's nothing short of a life-changing injury or illness that will change that. If you have human-averse hens or roos, after a year of trying with them you'll know for sure, then best to be rid of them as they can and will teach more trusting birds, and chicks, to fear and avoid and distrust you. Some chickens don't question the alarm call. Others will, but most automatically respect it, so even if they trust you, a chicken repeatedly vocally identifying you as a threat will still have its effect, and quickly too. They are quick learners.

Holding them is good, but better if you can get them to walk up onto your lap or arms for treats. If you do catch and hold, which I also do, make sure they relax in your arms before you let them go.

If they always spring from your arms like they've escaped a predator, instead of calmly walking/hopping off and not fleeing your immediate vicinity, then they're a dud as far as tame/trusting birds go. They've made their choice.

I repeat the exercise immediately if they keep exploding away from me when I let them leave my lap, but if I have to repeat it too many times with no improvement, say about 7 times in a week, then I know from past experience that no more attempts are necessary as they're too human-averse and/or plain stupid for my flock, and I get rid of them and don't breed them. Attitude is strongly heritable.

Animals that won't trust you make everything so hard and dangerous when it comes to simple things like handling them, medicating or treating them, etc; sooner or later you will have to do these things for their sakes, so best that your stock won't endanger you both while you do whatever is necessary.

Some people go with the whole 'I leave them flighty so when there's something wrong with them it's obvious because I can just pick them up without a chase and fight' --- problem being, by the time a bird that is terrified of you allows you to pick it up, it's often too far gone to be helped, and not only that, your touch is so stressful your very help is harming it. Regular handling enables you to spot needy cases before they are beyond rescuing, and gives your patients some trust in you and even comfort in your presence.

Even a tiny bird like this can permanently scar your face, blind you, etc., so please don't tolerate vicious or hysterical reactions to pressure or fear just because they're small.

On that note, chooks that routinely leap at your face when they feel cornered should be killed. That's a deliberate and effective escape mechanism that uses your automatic eye-protecting reflex against you, at risk of you losing your eyesight if you're not quick enough. It's no funnier when a sheep or cow jumps at your head to escape either, and no less deliberate; it's just a trait some family lines have, a learned behavior, and curiously enough they all have numerous other character failings as well. It's part of a whole nasty mentality that is more than willing to do harm even when circumstances do not call for it.

Best wishes. Hope this helps.