First of all, Jesus was not an unclean animal...second, His command was to DO THIS......remembrance was merely the reason to DO THIS.....do this is an imperative sentence which issues a command....remembrance is the reason to obey the command.
Sorry; but the COMMAND was given WAY earlier in Jewish history:
Exodus 20:24
You shall observe this rite as an ordinance for you and for your sons for ever.
The Jews KNEW that the Passover Lamb was an indication of the Messiah to come.
Jesus was pointing out that HE was that Lamb.
He was changing their 'rememberence' to Himself; away from the mere meat that was before them: changing the mere WINE into remembering His blood; about to be shed for them.