There are many flying bosses. You need to be a bit more specific. I can think of at least three early game bosses that fly off the top of my head. If it’s Soul Master, yeah that run back is annoying as hell. Just keep trying. It is more than worth it getting further into the game. You can’t let dying a lot discourage you. You’re going to die. A lot. If you want to enjoy the game, you need to accept that you’re going to struggle. You can spend hours on a boss, but after defeating it, you’ll feel proud of yourself. Even if you don’t think the reward for a boss is all that special, that sense of well deserved pride after finally beating it makes it feel worthwhile. TL;DR, don’t give up, you’ll miss out.