I never liked my music theory stuff. It wasn’t the concepts themselves: I found the concepts fascinating in themselves.
But how it’s usually taught is dry and lifeless and I grew to hate it as a kid.
Nowadays, a quick search though and you’ll find SOMEBODY who shows you the thing you want to know in a way that is compatible for you.
Ostinatos are “background” – made up of musical figures.
A musical figure is similar to a motif, but a motif is in the foreground whereas figures are background.
Both short though.
Ostinatos can repeat endlessly, making up a whole song.