That is an incorrect translation, not sure where you obtained it. Sanskrit words -
'vRtra' - means restrainer/a container of thunder clouds/overbearing containers/clouds;
'yoni' - generally means a container/bearer (only if using it when describing a particular human's origin is it used a equivalent for a female's womb);
'mAnava' - does not mean Manu, but ...
Rig Veda mentions purandara - पुरन्दर (one who destroyed cities). Rig Veda praises both Agni and Indra as purandara - पुरन्दर.
In praise of Agni: Rig Veda VI.16.14
तमु त्वा दध्यङ्ङृषिः पुत्र ईधे अथर्वणः। वृत्रहणं पुरन्दरम् ॥१४॥
tamu tvā dadhyaṃṃ ṛṣiḥ putra īdhe atharvaṇaḥ | vṛtrahaṇaṃ
In praise of Indra, Rig Veda II.20.7
स वृ॑त्र॒हेन्द्र॑: ...