Again, he was in extremis coma (dying). This was due to the primary cause of death by crucifiction: asphyxiation due to cardio-pulmonary congestion; i.e. fluid collecting in the pleural sacs around the lungs, making breathing impossible.<quoted text>
33 But when they came to Jesus and found that he was already ~dead,~ they did not break his legs.
34 Instead, <<<<<one of the soldiers pierced Jesus side with a spear, bringing a sudden flow of blood and water.>>>>>
35 The man who saw it has given testimony, and his testimony is TRUE.~He knows that he tells the truth, and he testifies so that you also may believe.~
When the soldier's lance pierced the sac, clear congestive fluid mixed with a little blood from the puncture would have drained out, relieving the constriction on one of the lungs. Immediate removal from the cross and lowering of the arms, hurried and jostled transport to the tomb at the other side of Jerusalem would have reduced the congestion on the other lung as well.
Spontaneously coming out of extremis coma, very like death and requiring an EEG to distinguish from actual brain death, does exist in contemporary literature. People actually declared dead by physicians using only a stethoscope have awakened very surprised (and surprising) in morgues. In extremis coma, the heart can beat as seldom a once or twice per minute. Most people just die.
Really, it's not as though they had much in the way of medical knowledge.
For me, none of this diminishes the message of Yeshua in the least.