'This' is literally 'that-here' — Proto-Germanic added a proximal particle to the demonstrative *that.
Used to identify a specific person or thing close at hand or being indicated or experienced.
From Old English 'þis' (neuter of 'þes,' this), from Proto-Germanic *þat-si, a compound of the demonstrative base *þat (that) plus the deictic particle *-si (here, this). The PIE demonstrative root is *tó- (that, the one). The '-si' suffix marked proximal deixis — pointing to what is near the speaker — as opposed to distal 'that.' Old English had a full three-gender paradigm: 'þes' (masculine), 'þēos' (feminine), 'þis' (neuter), but
'This' and 'that' are built from the same Proto-Germanic demonstrative root *þat — the only difference is that 'this' carries the suffix *-si meaning 'here' (proximal, near the speaker), while 'that' is the bare form pointing to what is farther away. Nearness and distance are baked into the very morphology.