Hey U_K!
That's basically what I thought. The MU has several candidates on the First One roster:
Eternity -- Time
Oblivion -- Entropy
Death -- Entropy
Infinity -- Space
Master Order -- Time
Lord Chaos -- Thought
Eon?
Of course, I haven't identified the First One of Good or Evil and I suspect Marvel has intentionally avoided this subject matter. Also, Death and Oblivion might be two aspects of the same being (likely) as they appear to be equally fundamental (perhaps Oblivion is the counterpart to Death in another universe which would explain the infrequent appearances). However, the other overlap involving Eternity and Master Order doesn't quite work as they often appear simultaneously in the same universe and MO is clearly a subordinate. This gives me pause regarding Lord Chaos.

By rights they should be First Ones, but the Marvel iterations seem to suggest that they are notably less than the likes of Eternity, Infinity, Death (and the rarely seen Oblivion), so maybe they are both 'merely' Old Ones.
That's basically what I thought. The MU has several candidates on the First One roster:
Eternity -- Time
Oblivion -- Entropy
Death -- Entropy
Infinity -- Space
Master Order -- Time
Lord Chaos -- Thought
Eon?
Of course, I haven't identified the First One of Good or Evil and I suspect Marvel has intentionally avoided this subject matter. Also, Death and Oblivion might be two aspects of the same being (likely) as they appear to be equally fundamental (perhaps Oblivion is the counterpart to Death in another universe which would explain the infrequent appearances). However, the other overlap involving Eternity and Master Order doesn't quite work as they often appear simultaneously in the same universe and MO is clearly a subordinate. This gives me pause regarding Lord Chaos.