In order to shield yourself from bots, you have to wall yourself off from brand new accounts. There’s no getting around that, since bot runners can spin up as many new accounts as they want. The best way for new human users to bootstrap is probably to assimilate into the web-of-trust of someone they know. And if you’re a real human joining Nostr, it’s almost certainly because you already know someone who’s on it. Just ask them to follow you and that’s reasonable proof to others that you’re not a bot.