The notion that different characters or pieces have different attributes seems to be one we take for granted today, but upon a quick historical survey, it is not so. After all, in chess, a pawn takes a queen or rook without any care for the latter's Constitution or Dexterity. Wargames such as Tactics used a combat results table rather than assign stats to individual units, which is something we even see in earlier editions of D&D (the weapons vs armours table).
Chainmail already had statistics such as armor class in '71 or '72, and obviously, the six attributes formed a key part of original Dungeons and Dragons in 1974.
Which RPG was the first to present stats as we know them today – a series of various attributes unique to an individual character? What inspired this system to present stats as it did?
For the purposes of this question, any statistic assigned specifically to a unit will do – "swordsmen have 5 hit points" or "mounted archers deal 7 damage" or "hobbits can carry 20 pounds of loot." I would also be interested in non-numeric attributes (as someone mentioned in the comments) as long as they fit the concept of stats and not lookup tables or similar.
Best Answer
The first commercially available RPG was Dungeons & Dragons (1974), by Gary Gygax and Dave Arneson, had character stats, though there were other proto-RPGs prior (see First RPG to use randomness during character creation for related discussion).
OD&D was derived from the wargame Chainmail, also written by Gary Gygax. Chainmail had a variety of unit stats, common in wargames by that time - movement, range, morale, damage, attack values vs other kinds of troops. The fantasy expansion had stats for individual creatures, but these are basic wargame stats - morale and a "combat" value (e.g. "Wizards - Fantasy Combat Table, Score 10") and "saves." Combat values were still represented in effectiveness vs a specific other unit.
Dave Arneson used the fantasy expansion to these rules to run his Blackmoor campaign, which had a variety of character stats, though not exactly the ones that made their way into OD&D.
The Braunstein games that spawned Blackmoor don't seem to have had stats (the historical record is vague here). Arneson introduced the more "personal" stats to the game via Blackmoor, according to this article
It appears to have been an organic process between Dave, his players, and borrowing from the general body of extant wargames that resulted in the first "modern" kind of RPG stats.