Regalo, Spanish for “gift,” comes from the Old French galer (“to rejoice; make merry”), with a re- prefix added for emphasis.
From the same root we get the the English gala, as well as gallant.
It makes sense: a gala is a big, merry, ball after all. Gallant is a bit more subtle: it meant, in old French, courteous — but earlier, it had originally meant, “amusing, entertaining,” from which we can see a clear relationship to making merry.
So it is noteworthy, therefore, that, good manners (being courteous) originally began as… being fun.
And all share the same g‑l root to make the connection clear.