Language
I see a lot of questions and theories based on English terms in the preliminary report.
"leur examen visuel montre que l’avion n’a pas été détruit en vol ; il paraît
avoir heurté la surface de l’eau en ligne de vol, avec une forte accélération
verticale."
is translated as
"visual examination showed that the airplane was not destroyed in flight ; it appears to have struck the surface of the sea in a straight line with high vertical acceleration."
The expression that is underlined (by me) is interpreted by some as meaning that the airplane fell almost vertically from the sky (like a brick would do), or that it dove nearly vertically into the sea.
The literal translation is "in the dircetion of flight", meaning, not sideways or backwards.
The "vertical acceleration" is treated by some as a sort of indication of speed of the entire aircraft. However, it is merely a description of the line along which the acceleration took place (and because the acceleration was in such direction that the movement of the parts was brought to a stop, a laymen would call it a deceleration). The deformation observed so far points to hitting the water with the velocity of the aircraft mainly along the longitudinal axis and downwards - that's all.
As to the terminology pertaining to the bodies: "relatively well preserved" is accurately translated, perhaps it means, besides "relatively in one piece" also "not yet decomposed" (sorry, not meant to insult any sensitive soul).