Learning a new champion is really daunting
If I try them in ranked I'll get crushed (obviously).
If I only use normals for new champs, I'll get into matches with people with poor teamwork and coordination, and probably get shit on anyway. The only difference will be a lack of jungle presence and team play.
Bots are absolutely useless, unless you literally don't know what the champs abilities do.
I used to be mid silver MMR, I've played Morgana up to almost gold (but lost patience for placements) and now feel like I can't play anything else without doing shit. Even champs I thought I was ok with feel like a slog. What do other people do when they wanna diversify their pool?