I imagine the usual 50 - 100 players are going to be the same people returning. I think the main issue is how easy the game is to understand and get used to for new players - especially younger players.
Personally, I think the UI is a bit too intrusive in the way that everything is coloured and bright in the tutorial, making it hard to know what to concentrate on. New players also don’t like having to read much text. I know you don’t have too much, but it could be clearer how the game functions. I have played Clash Royale, so I didn’t have much issue picking this up, however I can imagine the difficulty some might when there’s so many buttons that can be pressed.
Maybe consider blurring, greying out, or temporarily removing buttons for the tutorial as to not confuse players.
Also upon coming back to the lobby, you’re immediately thrown back into the tutorial. I’d suggest that the tutorial for selecting and equipping new troops should only show up when you open that menu (same for chest menu, etc.) - players will be smart or curious enough to click on these anyway, especially with the notification numbers on the buttons.

In the lobby, clicking the icons for troops at the bottom of your screen isn’t obvious with what it does. It removes them, but it’s not completely clear that’s what troops I have equipped - there’s no text saying that’s what it is. Maybe this should be on a separate menu.
I removed some, and then was generated new ones based on my collection. Instead of this, maybe a warning should come up telling me that I should review my equipped troops. This is nitpicking and isn’t too important for the new user experience, but knowing what it is at least would help new players.
Also, the equipping/unequipping process is a bit weird. It’d be nice to have to select a slot to replace in one go instead of clicking to unequip it, then clicking to equip the other.
I know from experience in Clash Royale that these 3 icons are the different battlefields, but it’s not clear as a new user. If the goal that I’m working towards isn’t clear, why should I bother trying to work for it?

The process of upgrading cards is tedious, having to click Upgrade, then Upgrade again, then Close, and then repeating that for however many times I can upgrade my cards (which is a lot sometimes). It’d be easier if it was just a single button I could keep pressing. Again a nitpick but helps the user experience (and so the new player experience too).
It’d also be nice to have a description of what your troops do when you hover over them in-game, so new players can try to work out which ones to use. Better/more clear animations would help with this a lot too.
I probably could’ve made this more concise, but I hope it helps you anyway. Consider yourself as a younger, new player, and try to see how your game might be confusing (since that’s usually the main factor). I like your game - it’s actually pretty fun. I think the main issue is just making things easier to understand.
And last thing, the issue isn’t originality. People might like both Clash Royale and Roblox, so they might think the combination is cool.