How could the messengers have prayed behind the Prophet in Al-Aqsa Mosque and then been in the heavens, and are they alive in a way different from us?

The Prophets are dead in relation to the people of this world, but they are alive with Allah. It has been established that the Prophets are alive in their graves, praying, and their souls enjoy this prayer. The Prophets are buried in their graves, except for Jesus, peace be upon him, for Allah raised him to Himself with his body and soul. The same is said about Idris. As for the Prophet’s — may Allah’s peace and blessings be upon him — vision of them on the night of Al-Isra wal-Mi'raj, it was of their souls, depicted in the forms of their bodies, except for Jesus, peace be upon him, whom he saw with his body and soul.