It replicates a full wallet to some extent, and that's the whole point of it, but it's missing the essentials to sign transactions. A watch-only wallet created with public keys or a master public key can't sign any transactions unless you made a mistake and imported the private keys/seed instead. You seem to be struggling with the terminology and understanding of how transactions work, so such a mistake is possible. The wallet you created can't know your keys unless you provided it to it. It's that simple.