This is the first Captain America where Steve Rogers (Chris Evans) will not use the title. So why is the character replaced? Well he is close becoming Public domain so in able for Marvel to keep ownership of Captain America, They promote less popular superhero "Falcon" and gave him the title Captain America.
In MCU, Steve Rogers travels back in time in 1940s to be reunited with his love, Peggy Carter. So in MCU timeline, Captain America is now an old man on his 90s after aging out after time travel.
He Gave his shield to Falcon and made him the new Captain America.
This is also the MCU debut who Redhulk, He was the father of Betsy, Hulk's wife. he hates Hulk/Bruce Banner so much but he ends up having the powers of his hated Son in law.

Many people are nervous it may flop, since its not just the actor they replace in this movie but the character Steve Rogers himself.
They launch Red Hulk probably for a future adaptation of Agents of Smash.
Agents of Smash is a team of Hulks composed of Hulk (Bruce Banner), His cousin She-Hulk, His wife Betty who became Red-Shehulk and his father in law Red Hawk.










