Are the champions you get in ARURF limited to what you own?

Came back to LoL yesterday and realized ARURF is up, my favorite mode. I played for 6 hours straight (literally) last night, and another hour or two today. And I've noticed in every single game I'm getting these basic ass champions like Zilean, Fizz, Trundle, Garen, ect. Now theres nothing wrong with these champions. But I'm tired of playing the same old boring ass characters that I've played a million times. So I'm curious if the characters I'm able to get is limited to what i actually own? Because i only own the basic ass champions because it takes weeks of stress inducing grinding to earn 1 decent character. I could've swore you were able to get any champion thats in arurf, no matter if you own them or not. But now I'm starting to think i have to play these basic champions the whole time. You guys don't even offer some pack to unlock like 5+ champions in exchange for $$$ like Brawlhalla for example. (as far as I'm aware theres no character pack bundle. but I'd definitely pay $10-$40 if it unlocked a good amount of GOOD characters) Also this isn't a hate thread or complaining thread, i just want to know the answer to my question (the title)