(If you're having second thoughts about your character and would like to play something else, that's okay! Happy to talk about other options.)
The background to the campaign is essentially as discussed in the thread: Once upon a time there were five young adventurers who met in a tavern, formed a party, delved dungeons, fought dragons, and achieved wealth, fame and success. You bonded together through the formative years of your lives, overcame great hardship and peril as a result of that bond, and then slowly drifted apart as your non-adventuring responsibilities grew.
(Yes, five. The fifth member of your party was a wizard called Theobald, now the world's greatest archmage.)
As far as character creation, you're welcome to use whatever (official) sources will best let you realise the character you had in mind. In particular, I'd recommend the options in Tasha's around customising your origin, so you can play any race without worrying about getting the right ASIs (the Custom Lineage is also a fine way to go).
Don't bother with a Background though, unless you desperately want to: instead, just gain two Skill Proficiencies and two Tool and/or Language proficiencies of your choice. Your Background is essentially "Legendary Hero", and the associated Feature is that people will treat you as such.
Equipment-wise, you can have any mundane equipment that you want, without limit. You can also select up to three uncommon, two rare, and one very rare magic item.
I'll also ask that you help me out with a bit of worldbuilding related to your character. Primarily, what organisation(s) are you connected to, what is their purpose, and what kind of resources are at their disposal?
Also, feel free to discuss ideas about specific heroic feats that you performed together in your adventuring days. This is more or less a Greyhawk-style fantasy world. Ask about anything you need to know, and I'll do my best to provide!
I think we should spend at least a week on this, and we'll see if we need more time at that point.