This is common misconception. The truth is that in HE every plaintext can be encrypted to (exponentially iirc) many different ciphertexts. During encryption one of those is chosen randomly. This makes dictionary attacks practically impossible.

Edit: HE scheme (lwe) works on individual bits. Meaning there are only two plaintexts (0,1). Each has exponentially many ciphertexts, only one chosen at random. They also share ciphertext space, meaning each ciphertext could be either encrypted zero or one.