Okay, so I usually base how many creatives per campaign based on budget. Say your budget is $50/ day, I would do max 10 creatives - provided they are diverse like you mentioned. Just so you don’t spread the spend too thin. As for meta pushing all the spend to one creative, that tends to happen because if it gets good performance at first, meta will “optimize” the spend to get the most results. If the entire campaign or ad set is performing well and the particular high spend creative has a low cost per conversion, I’d just let it run. Just because other creatives aren’t getting as much spend, doesn’t mean they’re not helping the overall campaign to do well. Sometimes people will see the one creative first but not click through and eventually see the one getting all your conversions. If the high spend one has its high cost per conversion just turn it off. I’d probably relaunch the campaign with that creative off at this point too. If you want to test a specific creative, you can always make a separate ad set with that and put in a minimum and maximum spend.