I'm still in my learning phase and I make many small projects as I learn. Is putting all of them on Github a good idea, if I want to put it on my resume in the future, or would having too many repositories on Github a bad thing?
A repo per project is not necessarily bad. However, don't create five dozen documentation projects, each of which is just a list of references. That's padding, and it'll be really obvious and annoying.
I've interviewed a candidate that created dozens of GH projects, each one just being a list of tools for various topics. So they'd have "Programming tools", "Security", "Databases", etc. They may have thought that on the surface it would show them as a well-rounded candidate, but if you dug into it, it was just that - a set of lists. Even AI generated slop that gets churned out by the dozens these days has more content than those projects did. Even worse, when asked about their experience with the tools, the candidate couldn't give a useful response. It was like asking about the Donner Party and getting an answer about birthday parties.