v esperanto net ni odnoj fonemi, kotoroj bi ne bilo v russkom ili polskom jazike
The phonemes /h, g^, u^/ are absent in Russian. AFAIK, /h/ is absent in Polish.
iz 2612 kornej, predstavlennij v «Universala Vortaro» (1894) tolko 29 mogli bit zaimstvovani iz russkogo ili polskogo jazika
Zamenhof was randomly borrowing words from different European languages. The fact that only 1% of them were taken from Slavic languages proves that Zamenhof was avoiding them.
The Alphabet seems to be the only feature of Esperanto influenced by Slavic languages. While the alphabets/orthographies of Western Europe are "traditionalist", the alphabets of Slavic languages tend to be more "radical", and this radicalism fit well the idea of radical international language.