Here's how Agent Davis died on The Avengers. His death was used to unite the titular superhero team during the third act, but it didn't take long for Coulson to get resurrected for ABC's Agents Of SHIELD spinoff series.
How and why he was still alive formed part of the mystery of WandaVision have much more explicit ties to their movie counterparts, but Agents Of SHIELD has its unique niche within the franchise.
One new character the series introduced was Agent Davis, played by Max Osinski. Davis first appeared in Agents Of SHIELD's season one episode "Repairs," and he played a recurring role throughout the series. He and Agent Piper also formed a fun partnership, but all that came to an end with season 6's "Leap." This season saw Agents Of SHIELD's title characters encounter Izel, a powerful being who also created the planet-killing Shrike parasites. In a key scene of "Leap," the agents are trying to stop Izel as she jumped from body to body, possessing them, including Davis, who she kills during a display of power.
In Agents Of SHIELD "Leap," Izel has infiltrated the Lighthouse base trying to find the Monoliths she seeks. During the possession scene she shows off powers, including forcing Piper to shoot herself in the hand, before making Agent Davis walk over to a ledge and dropping him off it while the others are powerless to stop him. Davis is killed in the impact, and Izel then possesses Mack and holds a pistol to his head, warning the others not to follow. It's a fairly shocking scene, and one that underlined the threat Izel posed even further.
The team would later gain revenge on Izel, with Melinda May killing her in the Agents Of SHIELD season 6 finale. While Agent Davis died during "Leap," he was later brought back by Piper's request as a Life-Model Decoy in the season 7 finale "What We're Fighting For."