There is only one ‘I’, and investigation will reveal that it is not a finite ego but the infinite self
Your comment that you are a little confused about the ‘I’ referred to in ātma-vicāra suggests that there could be more than one ‘I’, which is obviously not the case. As we each know from our own experience, and as Sri Ramana repeatedly emphasised (for example, in verses 21 and 33 of Uḷḷadu Nāṟpadu: ‘தான் ஒன்றால்’ (tāṉ oṉḏṟāl), ‘since oneself is one’, and ‘தனை விடயம் ஆக்க இரு தான் உண்டோ? ஒன்று ஆய் அனைவர் அனுபூதி உண்மை ஆல்’ (taṉai viḍayam ākka iru tāṉ uṇḍō? oṉḏṟu āy aṉaivar aṉubhūti uṇmai āl), ‘To make oneself an object known, are there two selves? Because being one is the truth of everyone’s experience’), there is only one ‘I’. When this one ‘I’ experiences itself as it really is, it is called self or ātman, whereas when it experiences itself as something else it is called ego, jīva or jīvātman.