When Jesus died, many dead elders of Israel rose from their graves during the earthquake and were seen among the people after his own resurrection. Having risen from long death, they too may have bodily ascended to heaven. The 24 elders in heaven came from somewhere! You didn't learn that in Sunday school. Matthew 27:51-53:

And the earth shook, and the rocks were split. The tombs also were opened. And many bodies of the saints who had fallen asleep were raised, and coming out of the tombs after his resurrection they went into the holy city and appeared to many.