My initial thought is, if the heart is not a pump, why can I feel my heartbeat in my veins in my wrist, my neck, my ear, and when I have stubbed my toe?
https://www.rsarchive.org/RelArtic/Marinelli/
“In 1932, Bremer of Harvard filmed the blood in the very early embryo circulating in self-propelled mode in spiralling streams before the heart was functioning.” — the mother’s heart pumps blood via the umbiolical cord ... Read even more