Transmigrating and Mutating to Become a God

Transmigration + special forces + alternate history + conquest + immortality + gods and demons + divine and exotic beasts + supernatural abilities and arts + the Myriad Worlds. The protagonist can travel between two worlds. Main world: a world of gods and demons, where supernatural abilities and arts are common, and divine and exotic beasts abound. Secondary world: a shared cinematic universe beginning in the 1960s. To be clear, this is not the history of the real world! Once the protagonist enters the secondary world, it too begins to undergo slow changes.