1) a lot of these names arent "odd". perhaps we need to learn your definition of the word.
2) America is known to be the great melting pot of the world. strictly going of american names you will get names that have influence from around the world. Stipe is American, born in the USA, but that name is Croatian.
3) because of mass migration and how language works (think of the similarities of the Romance language), certain words change over the years (ie spelling, how its pronounced, etc). an example of this is Colby, which is derived from Jacob, which is derived from Jacoby/Jacobi.
4) Some of these arent even their real names. BJ Penn's name isnt Baby, its Jay. Or, you have Kit, thats not his name. Kit is short for names like Christopher (which is his name). it is akin to calling Theodore "Ted"
5) You mentioned like 4 or 5 names from the bible, the number 1 selling book ever. Urijah is in the bible.
6) Perhaps you are from a small town and havent travelled much. many of these names are common
7) If you can name a celebrity with the same name its difficult to call it odd (although i can argue the other way for that too). Dana Carvey, for example, is a famous actor, costar of the movie Wayne's World.
7a) Did you know there was a super famous movie with a super famous quote using the name Forrest? its called Forrest Gump, and the quote is "Run, Forrest, run!"
8) Americans have been using crazy names more and more as the years go on. Main character syndrome? Perhaps.