Is it a true or false serpent ?
⚪ Satan appeared as a serpent
"ANGELS WHICH KEPT NOT THEIR FIRST ESTATE"
In their original estate all the angels seemed to possess the ability to appear in earthly forms - Satan appeared to Eve as a serpent, other angels frequently appeared as men, thus performing their ministry, appearing or disappearing as the work demanded.
Source : 🇺🇸 The Watchtower, July 15 1894, page 231 , page 231 
⚫ Satan used the literal serpent
[...], Satan, is referred to as "the original serpent," evidently because of his employing the literal serpent in Eden as his means of communication with the woman. (Gen. 3:1-15)
Source : 🇺🇸 1971 - Aid to Bible understanding, page 1472 + Cover