Incorrect. You claimed that biblical Christianity does not command us to do anything. To defeat that contention I do not need to show precisely what he commanded us to do but merely that he commanded us to do something. Nevertheless, I contend that he commanded us to commemorate the actions he had just completed when he said “Do this in memory of me”. To prove your original contention you would need to prove that he did not command us to do anything.
Okay, we may be finished before we start. If “this” was an occasional memorial when believers gathered, without any specificity or “sacramental” import, nor with any requirement of frequency or consequence (other than it might remind folks of the wonderful power of His death, burial and resurrection), then there is no substantial “this” to discuss. And, I am fairly busy here, so either get on with your definition of “this” or say goodbye.