I think we can state definitively there 'have been some forms of life that can self-reproduce' to slightly paraphrase you (since we are an example). Unfortunate

I think we can state definitively there 'have been some forms of life that can self-reproduce' to slightly paraphrase you (since we are an example). Unfortunately the opposite claim, that there have been forms of life that couldn't reproduce will be very hard to falsify, unless we happen to meet a very long-lived one. Self reproduction might be necessary but not sufficient to define life. Crystals reproduce, for example, but we wouldn't likely call that life?