Odin. The All Father. He's gone by a few names over the years. Odin has been alive for over a million years. The events recounted here: https://marvel.fandom.com/wiki/Odin_Borson_(Earth-616) can be taken as accurate up to the header 'The Modern Age'. Not that many people know about those events.
The Nine Realms (other than Midgard) are extradimensional. Yggdrasil really does connect them all. Heimdall really does stand guard over Bifrost. Asgardians, and other denizens of the Nine Realms, are, for the most part, magical beings though most of their power is innate to them and only a small number use actual magic. Unlike in the MCU, none of them are spacefaring.
To date, Ragnarok has never happened. Baldur has not died. Asgard has not been destroyed and it has never - NEVER - been in Oklahoma. Nor will it ever be. EVER.
