No limits on God. God set His limits on us. It was God that set the limits on Adam and Eve. All they had to do was obey Him when He said to not eat of that one tree. But someone told them, they really had no such limits--they would not die. Obedience to God sets us free from the bondage to sin. Satan still says we will not die if we do what we want and disregard what God says. It's just that now He is saying we will not die that 2nd death. And if you think the laws of God are just words on stone--they are a revelation of His character.
Levitical laws were not set in place until Zion. But that there was a sacrificial system since Adam and Eve is certainly in the bible or Cain and Abel would not have been making any such offering to God. And if it was only meant for them, no one else would have been making them. Abraham was doing them, Job was making sacrifices to God, and there was Melchizedec and tithes--These people didn't come up with these things on their own. The bible does not state every thing--it was an oral society back then---God spoke directly to those people.
Gen_8:20 And Noah builded an altar unto the LORD; and took of every clean beast, and of every clean fowl, and offered burnt offerings on the altar.
Noah knew abut clean and unclean animals. They went into the ark by clean and unclean.
The Sabbath was set in place at creation.
Gen 2:2 And on the seventh day God ended his work which he had made; and he rested on the seventh day from all his work which he had made.
Gen 2:3 And God blessed the seventh day, and sanctified it:
because that in it he had rested from all his work which God created and made.
Mar_2:27 And he said unto them, The sabbath was made for man, and not man for the sabbath:
Jesus should know--He was there that creation day. To deny the Sabbath as set at creation is to deny the God of creation. He created it for us. At Zion He stated again the reason for the Sabbath --
Exo 20:11
For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.
It was set at creation as a memorial of God's creative powers. It is He that created the world and it is He that decides what our duties to Him and each other are.
He gave His life for us in a very cruel manner, He gives us everything--He asks for one specific day a week for us to be spent solely with Him and for us to not work and the world has to argue about it because it interferes with their schedules.