I love this cartoon, but... No.
I'm sorry. My nerd side has become a kraken screaming to be released.
.
If juvenile centaurs can stand up, walk, and run at the stage of development shown, there is absolutely no reason that they shouldn't be able to hold up their heads. Colts become mobile soon after birth due to the high rate of axon myelination in their brains. Human babies can't lift their heads because of the inverse-- human axons myelinate very slowly, over a long period of time. (The process isn't actually finished until the human reaches their early twenties.) So, logically, if a centaur's axons myelinate quickly enough for them to stand at the stage shown, then it means their human halves would also have fairly good motor skills just about from the get go.
If you want to take this even further, it follows logically that centaurs become mentally mature earlier than humans do. Their brains would be fully developed by the time they were 3 or 4 (if not before.)
If that were the case, they wouldn't be able to walk until they were around a year old. You can't have one part of the body mature at one rate, while another part matures at a different rate-- mythological or not, biology doesn't work that way.
I'm sorry. My nerd side has become a kraken screaming to be released.
.
If juvenile centaurs can stand up, walk, and run at the stage of development shown, there is absolutely no reason that they shouldn't be able to hold up their heads. Colts become mobile soon after birth due to the high rate of axon myelination in their brains. Human babies can't lift their heads because of the inverse-- human axons myelinate very slowly, over a long period of time. (The process isn't actually finished until the human reaches their early twenties.) So, logically, if a centaur's axons myelinate quickly enough for them to stand at the stage shown, then it means their human halves would also have fairly good motor skills just about from the get go.
If you want to take this even further, it follows logically that centaurs become mentally mature earlier than humans do. Their brains would be fully developed by the time they were 3 or 4 (if not before.)