so this is a fun subject that usually gets touched on in regards to offensive native American portrayals so i think i can help you out in understanding the history of the Mascot though i'm going to go off on a bit of a tangent with Indian names v mascots at the end because it's something i've been interested in and rarely get to talk about.

i'm going from memory here but the first mascot was a midget John Mcgraw hired possibly Ty Cobbs' personal lucky charm L'il Rastus (McGraw was a manager of Baseball's new york giants. What you need to understand is mascots initially were not emblems of sports teams and instead were essentially "good luck charms." Thus explaining the ridiculous attire, masks, etc. that arrive out of them. as this article puts it

There was a time in American sports, predominantly in early 20th-century baseball, when deformed or degraded mascots were the norm. In Philadelphia, for example, both the Phillies and Athletics employed hunchbacked youngsters as batboy mascots.The custom grew out of a patronizing society's ignorant belief that the more socially outcast one was, the greater his worth as a good-luck charm.Humpbacks; dwarfs; those with crossed eyes; the mentally ill; and, of course, blacks and Indians were widely seen as talismans. It wasn't long until superstitious sports teams were cruelly using them for that purpose.

given the history of mascots i'd argue it's more luck and path dependence (for instance: the fact American sporting leagues don't have relegation systems is due to a large part to the path dependence set out by the founder of the national league Hulbert who created a strict central organization, created the territoriality rules and fixed the number of teams in a league) than anything else: European soccer didn't have Ty Cobb or Tug McGraw or Europe just had different sensibilities. Or something else but you need to look elsewhere for that information i'm afraid.

later on Mascots transitioned into the public face of the team they are today but the legacy of mascot history still impacts us today and can lead people to conflate mascot portrayals with the intent behind say native american names which is a mistake in kind since the intent behind native american names was to conjure up images of the noble plains indian warrior especially after us use of Indian imagery in WWI and in keeping with early 20th century beliefs that Indians were naturally superior athletes. You can obviously say both types of portrayals are problematic but they are in different ways and mascot imagery doesn't tell us much about the intent behind naming a team after native american warriors.

http://articles.philly.com/2014-06-23/sports/50774657_1_faust-mascots-connie-mack

if your interested in sports history questions i would recommend SABR (where the term sabermetrics comes from). It's a baseball history and research organization but baseball's longevity means it touches on a lot of other issues.

This is a slightly odd question given that

• European football teams do have mascots, if by mascots we're talking about men in suits who goof around on the sidelines of the game in progress.

• There are also "matchday mascots" in many clubs, a programme whereby young fans of the team can dress in the kit and lead out the players at games.

• Shamrock Rovers have Hooperman, but I'm unsure what is notable about him, or them.

The common use of mascots in football seems to date back to the 1966 World Cup held in England, when the organisers introduced World Cup Willie, a cartoon lion. Since then, every tournament has had its own mascot, and use has spread to other sports such as the Olympics.

Not sure where you got that idea. Most English Football League (soccer) teams have mascots. Newcastle Magpies, Sunderland Black Cats, Crystal Palace Eagles, Manchester United Red Devils, Norwich Canaries, Arsenal Gunners, Derby County Rams, Sheffield Wednesday Owls... there's loads of 'em!

Could you clarify what you mean with 'UEFL'? I can't find any google hits on the term and I'm not familiar with it.

Everton have two - Changy the Elephant (part of the sponsorship with Thai brewery Chang Beer) and the more traditional mascot, the toffee lady. A young girl dresses up like a (now dead) traditional toffee store owner and throws toffees (Everton mints) into the crowd.

http://www.whoateallthepies.tv/wp-content/uploads/2010/07/PA-9200646.jpg