I don’t think you’ll get consensus on the “it’s disrespectful” reasoning. It might not be inherently religious (although most religions I’m aware of expand upon it to specific procedures or prohibitions) but “respecting” the vessel which once contained a life seems very much tied up in sentimentality and woowoo more than sound reasoning or pragmatism. It’s just engrained into social norms at this point but, purely speculation, burial and burning were probably done for the same reasons other animals do it - you don’t attract other predators or suffer the scent of death inviting maggots, flies and other vectors for disease. It probably became more ritualistic and religious over time. If I’m dead someone can dangle my lads from their rearview like a pair of fuzzy dice for all I care - which will be not at all because I’m dead.
I don’t think you’ll get consensus on the “it’s disrespectful” reasoning. It might not be inherently religious (although most religions I’m aware of expand upon it to specific procedures or prohibitions) but “respecting” the vessel which once contained a life seems very much tied up in sentimentality and woowoo more than sound reasoning or pragmatism. It’s just engrained into social norms at this point but, purely speculation, burial and burning were probably done for the same reasons other animals do it - you don’t attract other predators or suffer the scent of death inviting maggots, flies and other vectors for disease. It probably became more ritualistic and religious over time. If I’m dead someone can dangle my lads from their rearview like a pair of fuzzy dice for all I care - which will be not at all because I’m dead.