"Pixel Art"
Pixel :
is formed from the words of Pix=Pic(picture) and "el" the start of element. it is a unit of measurement, a basis/part/block of a picture.
Art :
an alternative/older word for skill or craft, a measure/category/scale of ability.
early 13c., "skill as a result of learning or practice," from Old French art (10c.), from Latin artem (nominative ars) "work of art; practical skill; a business, craft," from PIE *ar(ə)-ti- (source also of Sanskrit rtih "manner, mode;" Greek artizein "to prepare"), suffixed form of root
*ar- "to fit together." Etymologically akin to Latin arma "weapons."
https://www.etymonline.com/
"Pixel Art" a term that was coined after the advent of 3d graphic, to categorized/refer to what seems an older/lesser/limited graphic visuals. Yet on the very basic of their words there is no core/basic/fundamental difference for they both (3d and 2d graphic) digital and drawn from pixel placement, they are both consist of blocks. The difference is in scale of size & color, one can take a 3d game such as one among
"Call of Duty" and lower its resolution down to 480x320(or similar) and behold the pixel are made apparent, they are revealed. Another example would be changing quality to lowest in abode Flash will show squares/pixels. Even one's vision is based on pixel if compared to eye-cones, the difference is that the human eye has millions of them, a much higher resolution.
On Both accounts of 3d & "Pixel Art" are hand by hand a manual input using a digital screen. as if the "artist" as not designed, as not drawn, as not placed the instruction on which the computer generates/create/copies without fail one form simply allows better, more efficient ways ,more impact, more rate of data transfer towered one's brain. Back then it was the relatively advanced form and if the developers/artist of these times were here today given equal circumstances(times is not an issue), they would have used the most advance tools that allowed the better graphics which is the 3d graphics that can allow flexibility in resolution and color yet the same can not be said vice versa even with a most advance AI for a single block for a face does not allow much details to work with.
Both 2d and 3d are made by human thus handmade/manual and are shown on digital screen(which is flat, shows 2d image), using pixel as units, yet the former and lesser form is the one refereed to "Pixel Art", the latter is excluded while both fit the category/term.
Biologically, as one who measured his eye sight, when playing an old game such Zeus(city building game), one can notice the deterioration of the sight, your vision becomes blurry. This does not happen often with more detailed/advanced graphics despite the similar long length of play time. This can be explained on the saying "use it or lose", lower graphics (color &pixel scale) cannot make full use of the entire eye spectrum, they do not provide the detail and color to stimulate all the cones, that can result in strain one can assume some eye-cones are overused and other left to wither. This makes playing an older games an issue for these they eye sight is a concern for good games are engaging for hours. Having poor graphics("Pixel Art") on a good game only worsen/enlarge/deepen their ills for they are bad on the sight.
The word Art in general is often misused to praise, the issue that they often praise the lower/lesser/backward rather then the higher/greater/forward. yet "Pixel Art" is not without merit for the lack of details simulate the brain to fill the gaps and for these lacking in drawing skills a fixed unit makes it harder to "screw up",show deformity on such rigidness. In fast paced games such as
"Children of Morta" the action can distract from their faults. The fact remains that the best 3d will suppress the best 2d and thus require more skill from the crater/developer/creator thus deserve the better praise/elevation/mention with the drawback of needing a higher/better/advance hardware.
On the basis/scale of image detail/info per time provided; "Pixel Art" is the equivalent of caveman drawing, a level/rank above letters for image.