Well now We're gettin into my childhood, and it's lookin good.

A titanosaur sized blue bull? :o

He's from an American folk tale called Paul Bunyan, which is about a giant lumberjack and his giant blue ox named Babe. So basically America's macro sweetheart lmao

Huh..how interesting :P Even if he'd make environmental groups moo in fear :p

YEAH it is a really weird folk tale to have... it surfaced around the time of western expansion so all the stories I know are like, Paul digs a big fucken hole in a mountain for a train, Paul and Babe clear a forest, Paul and Babe eat a shitload of pancakes and go to sleep
No time for consequences America wants to see a big blue ox eating giant pancakes NOW

Then again the settlers of the newly formed America didn't really have their own folktales [They ignored the Native Americans though...of course], unlike say in Scotland where I live, which has a rich backlock of myths of and legends. Everything from Brownies, little helpful fairies that live near your fireplace to the terrifying Nuckelavee that lives deep in the sea :o

Paul Bunyan does seem like the perfect symbolic representation of manifest destiny, now that you mention it. A literally larger-than-life personification of the domination of the continent. Not entirely unlike other semi-mythic early "hero" figures such as Daniel Boone, John Henry, Bill Hickock, Jim Bowie, George Custer, etc...

The Native American folktales are loved too, but in typical fashion have a tendency to get buried by the white folks' stories of the heroic domination and plunder of the unruly, dangerous wildlands and all of those primitive Godless heathens...