Sports subjects especially baseball made up only a very small percentage of what was put in packs from the late 19th to early 20th century.
Keep in mind that many people couldn't read or write. Many of those that could didn't have easy access to books, TV or the internet like we do either. So seeing far off worlds, exotic creatures, beautiful women, flags, random facts, jokes etc. was very cool.I suspect that in many ways seeing an exotic creature on a card had more zing than the local ball club and players to many.
All of the inserts were popular to those who cared. Some subjects more than others depends on what tickled your fancy. Those who liked them collected the heck out if them, pasted them in books, pinned them on walls etc. Then there were the folks who didn't care and simply tossed them in the trash. Forget about who might have traded a bird for a Wagner....think of the guy who tossed it in the trash.
Cheers,
John