Children don’t think about language before they become fluent. Nobody has told them they should think about grammar rules, or has taught them how to do it. As adults we would also do better to focus on meaning over form.
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Eeeeh. I dunno. Depends what you mean. We obviously don't/can't learn like children
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We obviously can! I've learned a language as an adult with only input without studying or thinking about grammar or sentence order or pronunciation and without translation.
You are taking into account one aspect of language acquisition and applying it to second language acquisition. It's more complex than that. We adults have much more knowledge of the world which allows us to use context. That's one huge advantage we have over children.
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Also just the very fact that second language acquisition is an entire field of study should give you a hint that we don't learn "like" children. But we can get inspired from them at best.