As PPD said, your render type needs to be cutout
For example see here
https://github.com/TheGreyGhost/MinecraftByExample/blob/master/src/main/java/minecraftbyexample/mbe03_block_variants/StartupClientOnly.java
and some more background info here
https://greyminecraftcoder.blogspot.com/2020/04/block-rendering-1144.html
-TGG
From my experience the motion of player is (0.0, -0.0784000015258789, 0.0) when still is because there's gravitational (downward) acceleration, and the unit should be blocks/tick.