The Help action clearly states
You can lend your aid to another creature in the completion of a task.
Even if you read it separated from the second paragraph
Alternatively, you can aid a friendly creature in attacking a creature within 5 feet of you.
Here, Crawford clearly states that "friendly creature" referes to someone else, not yourself, and even explains that, as in Inspiring Leader, if you could target yourself, it would state it explicitly.
Is a creature its own ally? Also probably no.
I would like to add another point: even if in 5E it might not be explicitly written, it is almost certainly intended that "an ally" is another creature (Note: As soon as I wrote that, I sanity-checked myself and got some doubt. Then I opened this question, so refer to it in case I'm wrong here). Check, for monsters from the Monster Manual, the feature
Pack Tactics. The wolf has advantage on attack rolls against a
creature if at least one of the wolf's allies is within 5 feet of the
creature and the ally isn't incapacitated.
If the Wolf counted itself as an ally, this feature would be "the Wolf always has advantage on attack rolls", since it can only attack from melee (within 5ft.) and can only attack if he is not incapacitated. If this was intended, it would probably just say so.