Shapsei (Shopsy, Shepsel, etc.) is a Yiddish form of the Hebrew name Shabbatai.
I have at least four Shabbatai/Shepsels on my tree. The generation they were born in probably influenced the names they went by in English.
The two born before 1880 both went by the name Samuel or Sam.
Another, born in 1903, was a Sidney.
The fourth was born in 1929 and at various times went by the names Salven, Selwyn, or Shep.