While this statement is true, what is also true is that the brain is the only organ we’re unable to fully understand, replace (as in through organ donation), and it’s what makes us sentient. This is why Row v. Wade had a specific fetal age up until which abortion is permitted. That age coincided with the age at which the brain is developed and the fetus becomes a child which could be delivered. Most of the red-state laws are restricting abortion after the heartbeat can be detected.
All I am saying is that it makes perfect sense, from the biological point of view, why the heart is one of the first major organs to develop: it’s main job is to deliver nutrient-rich blood to all other organs so that they can develop as well. But despite that, its not the heart that makes us human, it’s the brain.