That's almost true - there often is also some out-of-bounds communication about that code before the smart contract is implemented, which can help establish intent, which matters a lot in resolving disputes about a contract.
But the actual contract terms between the parties and facts like is this contract valid at all, who owns what and who owes what to whom are ultimately determined by contract law, not by the smart contract, like it or not. The smart contract may determine possession of certain things, and in many cases it would be uncontested and there it has a purpose of just doing the contract settlement automatically, but as soon as there's a dispute, then the legal ownership and any claims would be settled according to contract law, not according to what the code says.
But the actual contract terms between the parties and facts like is this contract valid at all, who owns what and who owes what to whom are ultimately determined by contract law, not by the smart contract, like it or not. The smart contract may determine possession of certain things, and in many cases it would be uncontested and there it has a purpose of just doing the contract settlement automatically, but as soon as there's a dispute, then the legal ownership and any claims would be settled according to contract law, not according to what the code says.