He sounds very bright, at the least. If I were you I would continue with songs, reading to him every day, and introduce a toy keyboard without pressure, and see what he does. Age appropriate music instruction is excellent for brain development, if he enjoys it. Yet, even if he turns out to have a genius level IQ, I agree with you that it’s really important to allow children to be children. Studies show that social and emotional skills are even more important than IQ to happiness and success in life. So you want him to be challenged, without making learning a grind. Best wishes!