The whole thing is basically a capstone to the Fox superhero universe:
Blade
Blade 2
Blade 3
The Blade films are from New Line, a Warner Bros company, which is why it wasn’t included in the mid-credit montage. It’s included because many people (including myself) count it as the first modern demonstration that Marvel movies could be good and it was the first building block for the MCU - a proof-of-concept if you will.
There are lots of references that will absolutely go over your head. The whole thing is basically a capstone to the Fox superhero universe:
Blade
Blade 2
Blade 3
Daredevil
Elektra
Fantastic Four
Fantastic Four Rise of Silver Surfer
X-Men
X-Men Origins: Wolverine
Logan
Deadpool
Deadpool 2
Pretty much the only ones they missed were Ghost Rider and F4antastic Four.
The Blade films are from New Line, a Warner Bros company, which is why it wasn’t included in the mid-credit montage. It’s included because many people (including myself) count it as the first modern demonstration that Marvel movies could be good and it was the first building block for the MCU - a proof-of-concept if you will.