Whether the word बराह्मण - brAhmana was used in Rig Veda with reference to Varna/Caste system?

Rig Veda II.36.5 says

eṣa sya te tanvo nṛmṇavardhanaḥ saha ojaḥ pradivi bāhvorhitaḥ |

tubhyaṃ suto maghavan tubhyamābhṛtastvamasya brāhmanādā tṛpat piba ||

Translation of Ralph T.H. Griffith is as follows:

This is the strengthener of thy body's manly might: strength, victory for all time are placed within thine arms. Pressed for thee, Maghavan, it is offered unto thee: drink from the chalice of this Brahman, drink thy fill.

Translation of H.H. Wilson (p.183) is as follows:

This (libation). Indra. augmenter of thy bodily (vigour). favourable of old to the resistless strength of (thy) arms: it is effused. Meghavan. for thee. it is brought to thee from the Brahmana. do thou drink and be satisfied.

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Both the translations are giving the meaning of from brAhmana. Though the word बरह्मा - brAhman was mentioned in II.1.2, it indicates the Almighty. However, here the word brAhmana was used.

In Rig Veda X.90.12, बराह्मण - brAhmana was used indicating one from Varna system, along with kshatriya, Vyasya and Sudra.

However, in the mantra in question, the word brAhmana alone was used that to requesting Indra to take oblation from a brAhmana.

Now a question arises as to whether the word बराह्मण - brAhmana was used in Rig Veda, with the meaning of a person from Varna/Caste system?

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Apart from in Rig Veda II.36.5, as mentioned in my question, the word brahmana was used in Rig Veda, here and there.

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Rig Veda II.43.2, dedicated to Kapiñjala, says

udghāteva śakune sāma ghāyasi brahmaputra iva savaneṣu śaṃsasi | vṛṣeva vājī śiśumatīrapītyā sarvato naḥ śakune bhadramā vada viśvato naḥ śakune puṇyamā vada ||

Thou like the chanter-priest chantest the Sāma, Bird; thou singest at libations like a Brahman's son.

Even as a vigorous horse when he comes near the mare, announce to us good fortune, Bird, on every side, proclaim in all directions happy luck, O Bird.

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In the mantra,  the word  brahmaputra was used.

The brahmaputra - brAhman's son, will sing Sāma Veda at libations.

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The major mantras of Sama Veda are from Rig Veda.

 I don't think the word brAhmana had been used with the meaning of Varna system, as the mantra was composed by a Sage, who was a dhrastha that heard from the DIVINE, apart from being a poet.

So that cannot and will not, in my opinion, use a word to indicate something, which is not DIVINE.

Further, in the 2nd mantra from Rig Veda II.43.2, the word used was brahmaputra - Brahman's son. It must be viewed in esoteric sense only, which will mean only the son of Almighty, ie., a brAhman by himself, in spiritual sense.

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So the word brAhmana was used in Rig Veda in the sense of a Realised one or Jnani only.