Consider, for example, the following verses:
الَّذِينَ إِذَا أَصَابَتْهُم مُّصِيبَةٌ قَالُوا إِنَّا لِلَّهِ وَإِنَّا إِلَيْهِ رَاجِعُونَ
Who, when disaster strikes them, say, "Indeed we belong to Allah, and indeed to Him we will return."
فَمَا كَانَ دَعْوَاهُمْ إِذْ جَاءَهُم بَأْسُنَا إِلَّا أَن قَالُوا إِنَّا كُنَّا ظَالِمِينَ
And their declaration when Our punishment came to them was only that they said, "Indeed, we were wrongdoers!"
Quran.com maps إِنَّا to "indeed we" and وَإِنَّا to "and indeed we" (2:156) and also maps إِنَّا to "indeed we" (7:5). However, this seems to be derived from أنا (ʾanā) meaning "I". Perhaps there's some nuance here I'm unaware of (I'm only just starting on the Arabic alphabet).
Question: Why is إِنَّا translated to "indeed we"?