For Christ did not enter a sanctuary made with human hands that was only a copy of the true one; he entered heaven (τὸν οὐρανόν) itself, now to appear for us in God’s presence. 25 Nor did he enter heaven to offer himself again and again, the way the high priest enters the Most Holy Place every year with blood that is not his own
NOTA BENE: sanctuary here is the heaven.
Since Jesus "entered heaven" to offer himself, he is not still offered (=he is not still killed), during the action itself of entering heaven.
in other terms, during the his entry to heaven (the "sanctuary"), Jesus is still living, he is not still killed.
Only once Jesus goes beyond the curtain of the celestial altar that is in heaven, only in that precise moment, Jesus is killed.
Hebrews 6:19-20:
We have this hope as an anchor for the soul, firm and secure. It enters the inner sanctuary behind the curtain, 20 where our forerunner, Jesus, has entered on our behalf. He has become a high priest forever, in the order of Melchizedek.
This is pure mythicism.