Is that blood then? Cause that's kind of a lot of blood, especially considering the usual depiction just involves like a few trickles and rivulets, not whole-ass sheets of blood enough to cover even a startlingly short adult.

People were a lot shorter back then

Not that much shorter. The average height for men in ancient Rome, taken from remains recovered from Pompeii/etc, was, to low-ball it, 165cm (5'6") (I can't find a link to the study itself, but it's quoted below), while the global average height today is 5'8", so people were only a couple inches shorter on average 2000 years ago. I suspect the range between minimum and maximum height is greater today because many people near those extremes have health problems that tend to be fatal without treatment, so that may skew perspectives.

The major samples from Herculaneum and Pompeii reveal the stature of the ancient adult body. The average height for females was calculated from the data to have been 155 cm in Herculaneum and 154 cm in Pompeii: that for males was 169 cm in Herculaneum and 166 cm in Pompeii. This is somewhat higher than the average height of modern Neapolitans in the 1960s and about 10 cm shorter than the WHO recommendations for modern world populations.

• Laurence, Ray. "Health and the Life Course at Herculaneum and Pompeii." Health in Antiquity. Ed. Helen King. London: Routledge, 2005.

Now let's do some pixel-counting to figure out how tall big J is in that image. The cave is 640px in height and it's indicated that it's 6', while the J-man is 465px tall.

6' *12 = 72", 640/72 = 8.89px/in.

465/8.89 = 52.3"

So shorty over there is 4'4" tall, or more than a foot shorter than the average height during his lifetime. Also, can I just say: Hell yeah, I fucking nailed it when I guesstimated 4 and a half feet tall in my original comment.