While the artistic merits of these people is without doubt, also consider that the ruling Medici family had a vested interest in establishing Florence as a cultural and political center of its time. It's not like other cities of the 15th century did not have any remarkable artists (particularly in Italy), but Florence is a prime example of a political entity that used soft power to promote its art(ists) and thus itself.

I think in any similarly sized group of people you will have talent like that, that could flourish in the right conditions.

It's a good argument for basic income tbh.

Wait, what happened to Donatello?

Look at all that ninja power! I didn't know there were other turtles too.

you forgot Ezio Auditore!

They had their names written down quite a few times, that's for sure