So here's the general idea of the reworked lore. Everything is subject to change, but this time I've actually done some slight research instead of basically making the whole thing up.

Our point of departure is around 15,000BC when humans first crossed into the Americas. Instead of all the large animals going extinct, they're domesticated. This means that the Native Americans have access to horses, giant beavers, and giant sloths in South America.

Polynesian ships find their way to the Americas, and while it's too far for reliable trade some aspects of their ships are reverse-engineered. When exactly this would have been I'm not certain, but definitely before the 15th century.

Vinland is more successful and essentially a trade secret among Norse sailors. Word of how to get there is on a need-to-know basis, plus medieval Europe wasn't quite ready for large-scale colonization. Vinland also spreads smallpox to the Native Americans, however by some miracle the disease is far less devastating, killing only 40%-60% instead of up to 90%. This would lead to massive social and economic reforms in the Americas in the same way that the Black Death did in Europe.

With the knowledge that Europe exists thanks to Vinland (Norse sailors are less guarded about telling the Skraelings all about Europe), some enterprising state sends out explorers along the trade winds. In the north Atlantic the trade winds form a circle going clockwise; if you started from Virginia you'd sail up the eastern seaboard, past Iceland, down into Ireland and Cornwall, then down the coast of France into Spain, Portugal, and eventually Morocco before the winds take you west again into Central America (or Mayan Territory in this timeline).

The American Indians make landfall in Ireland in 1453, the same year that Constantinople falls. Instead of Neuteo being in Spain, the large American Indian European colony is instead in Ireland. Ireland is ruled by a King of Ireland who is of American Indian descent (I haven't decided which group yet, this may change due to balance, but currently I'm leaning Powhatan). American Indian excursions into Europe are limited due to the west coast being controlled by mostly a few kingdoms (Portugal, Spain, France, England, and Norway via Denmark), so Ireland and perhaps parts of Scotland would be the only parts conquered/colonized. This does also change colonization throughout the rest of the world, although I haven't looked too far into it yet; naturally if Ireland is conquered then Irish Bengal won't exist though!

I've also decided to redraw the map to include more American Indian states. I have a hand-drawn map I'm not going to upload, but going from top to bottom in N. America using modern names for convenience:

Inuits control most of Alaska, Yukon Territories, Northwest Territories, Alberta, the east half of British Columbia, and the parts of Montana and Idaho above the Missouri river.

Haida control Vancouver Island and Queen Charlotte Islands.

Chinook control the Alaskan panhandle, the west half of British Columbia, and Washington state.

Cree control Nunavut, Manitoba, Saskatchewan, and Ontario.

Vinland is under Scandinavian control and controls Quebec.

Yokuts control Oregon, California, and Baja California.

Shoshone control Nevada, Utah, Colorado, Wyoming, and the parts of Idaho and Montana not controlled by the Inuits.

Iroquois control W. Virginia, Pennsylvania, Ohio, Vermont, and upstate New York. Their southern border is the Appalachian mountains.

Mississippi control Minnesota, both Dakotas, Nebraska, Kansas, Oklahoma, Louisiana, Mississippi, Alabama, the west part of Tennessee, Kentucky, Missouri, Iowa, Illinois, and Indiana.

Powhatans control Maine, New Hampshire, Massachusetts, New York south of the Appalachians, New Jersey, Delaware, Maryland, and Virginia.

Cherokee control the Carolinas, the east part of Tennessee, and the north half of Georgia.

Hopi control Arizona, New Mexico, and Sonora.

Guales control the south half of Georgia and Florida.

Wichita control Texas

Coahuiltecs control Chihuahua, Coahuila, Nuevo Leon, and Tamaulipas.

Mixtec control Guerrero and Oaxaca.

Maya control Tabasco, Chiapas, Campeche, Yucatan, Quintana Roo, Guatemala, Belize, El Salvador, Honduras, Nicaragua, Costa Rica, and Panama.

Aztecs control the rest of Mexico not previously mentioned.

Caribbean Federation controls the entire Caribbean.

Again these are rough areas, and since populations/industry won't necessarily match up with our own timeline some areas may be more or less valuable than expected.