Bienvenue = welcome
(It is sometimes helpful in understanding French to look at the real meaning of all the parts of the word or phrase.)
Bienvenue seems to be made up of a few familiar words
bien = good
venue = arrival
You might recognize ‘venue’ from such English/French words as ‘Avenue’, which means pretty much the same thing in both languages. An Avenue is a road either for people or cars (or horses, because they wouldn’t have had cars when the word avenue was first coined.)
One might say a traveler ‘arrives’ on an avenue or road. And one might greet that traveler by saying “Good arrival” = Bienvenue.