Because” isn’t a conjunctive adverb; it’s a subordinating conjunction. Subordinating conjunctions connect subordinate clauses (aka dependent clauses) to independent clauses in a single sentence. For example, “I went to the beach because it was sunny.”
Conjunctive adverbs (e.g., “however,” “moreover”) are adverbs that act in a similar way to conjunctions, linking the ideas in two sentences or statements together. They can link independent clauses with the help of additional punctuation. For example, “it was sunny; therefore, I went to the beach.