I think you are mixing precedence of two concepts: Ending the list item as a whole and a paragraph continuation.
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When the parser sees the 3rd line, first of all it has to decide whether the line is part of the list item started on the preceding line. It is not because of the rule “if can be interpreted as a list, no lazy continuation and interpret as a list”.
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Then the parser needs to test, whether it is a new item of the same list: No it is not (the mark endings do not match).
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So, the parser has to conclude the 3rd line starts a completely new block. And starts analyzing that, to eventually see it is an ordered list.
The rule about list starting with 1 does not play any role here because the paragraph is already implicitly ended when the list item it lives in ends.
The specification sometimes makes it quite complicated to get all the precedence among the many rules it provides. So if you’re implementing a new parser implementation, you may perhaps find this helpful: https://github.com/commonmark/commonmark-spec/issues/438#issuecomment-476867464 (note the Lazy continuation line has very low precedence).