I mean even The Originals cannot assume the form of any person that wish, they can compel people but can't assume anyone's form, but Silas has this power and everyone is unaware of it (which is both awesome and really dangerous). Even the powerful Bennett witch Bonnie has failed to realize that her companion is not Shane, but Silas. This shows the level of extreme deception and manipulation that Silas has, and how high is the level of threat that he possesses to everyone around him. Originals and regular vampires can compel people and take over their minds, but Silas takes over people's sentiments/ emotions and then their minds so his victims have no way to fight him off.
I am even surprised that everybody just let Bonnie go to her house instead of keeping an eye on her along with Elena since she is vulnerable/ unstable cause of Jeremy's death too 🤪. They didn't even think what if Shane came back for Bonnie to fulfill dropping the veil/ massacring people using Bonnie.
Rest in Peace Jeremy 🥺, and Rest in Pieces Shane 🐷