Given how many surnames are occupational (Fletcher, Butcher, Smith) I'd suggest that historically your "rank, profession or occupation" (as the Victorian census put it) was a major part of "structure, meaning and belonging". Especially if you go back to the era of apprenticeship and guilds.
I do wonder whether the moving away from the "career for life" mould has some part to play in the ennui that so many modern people seem to feel. Certainly some of the life events I'm proudest of over the long term are achieving professional qualifications - for instance commissioning as a military officer. It is a standard that society recognises your having reached, carries a degree of prestige and helps give a sense of place in the world.
In general, humans are interdependent for survival. Not like wolfes (independent) or ants (dependent). Everyone likes to feel useful, on a survival level, to others. It is like genetically built in (healthy) narcissism. UBI will keep people alive, but they must initiate meaning for themselves.
IMO, getting structure, meaning and belonging from your workplace is a fairly American phenomenon, and is a pretty poor place to get it. The traditional places to get this were from your church and family.
There are much better social constructs than the workplace. UBI should allow them to thrive. Let people self-organize according to their hobbies and taste rather than being thrown together by their job, and I think society will be much improved.