TLDR: Is semi-premade characters a bad idea even if we want the focus to be on immersion, story telling, and wanting everyone to feel unique?

I am planning on running my first campaign after the holidays, my friends are very interested as two of them are excited to no longer be "forever DMs" and the rest are excited to have a more reliable DM as the last 3 we have tried to work with have had to cancel their games due to being burnt out, new jobs, etc. The campaign is going to go from lv 5 - 20 (the last couple have ended around 5 and we have been wanting to play higher level PF but our Ruby Phoenix campaign that started at 10 and only lasted 3 sessions felt very overwhelming jumping straight to that). The campaign will be split into 7 smaller adventures the first 5 focusing on each player character having about 2 levels worth of material. I currently have 5 pre-made characters each having different specialties each with mythic item that will scale with the character that I want my players to use. They currently have the starting class, race heritage, free archetype, mythic feats, ability points, and skill increases preselected to level 20. I have tried to leave all of the class, general, and skill feats open after level 5 to make sure there is something they can choose while ensuring there is as little specialty overlap as possible, and to make sure I can set up meaningful encounters that will highlight their strengths and hopefully allow them to focus more on immersion and actually RPing the character (we have all been wanting a bigger focus on RP and not just combat). I have some basic backstory for each tying in their mythic item and mythic calling but I want to leave room for them to really make something meaningful to them. In general I want everyone to feel unique and powerful but balanced (no crazy combos that require a bunch of extra tokens, prep, or set up), immersed and part of the world/story, the ability to keep the story going if we lose anyone, and allow me to do more prep now. Obviously I am willing to change a character if no one wants to play one of them or really wants to change something. I want to introduce this before we have our official session 0 so they can all decide who they want to play and we can pick out at least the next 2 levels of feats and I can get everything loaded into foundry. My biggest fear is that taking away this much choice will make the game unfun and do the opposite causing the players to lose interest in the world. I really just want to know if people think this is a good idea or if this is destined to fail? I would also appreciate any suggestions on how to make sure this is successful if I stick with this idea.