In early game, dragons are just NIGHTMARES to try to kill or escape. I have been killed by dragons in Minecraft ALOT. But I figured out a way to escape dragons and kill them in early game. The thing that helps you do this is from Lycanites Mobs mod so you have to download that to.
This master weapon is... a Uva raptor. They have 30 health. You may ask "How is something that has less health than a hippogryph going to be able to escape a dragon in quick enough time that it does not get turned to DUST by a dragon?!?" Well the key is... its speed. ITS SPEED IS SO OVERPOWERED!!! Also theres a weird glitch that makes the Uva raptor Jump like thousands of blocks... The way you kill a dragon with this is just use a bow while rounding the dragon. You can basicly do this in iron armor if you have a good enough bow that it kills the dragon quick enough. Also they are fairly easy to get, Just right click them with avian treats (crafted with some cooked chicken and bones) and a soul stone (I forgot what the recipe is) to tame it. You will also need a saddle. AND Uva raptors are pretty rare. So you can go with a Vento raptor instead, because there alot more common (but idk if they can jump thousands of blocks)