It's (generally) accepted that Proto-Indo-European (PIE) evolved into the subfamilies Proto-Italic, Proto-Germanic, and Proto-Iranian among others.
English uses a Latin Writing system which evolved form a Greek writing system (which evolved from a Phoenician writing system, which probably evolved from an Egyptian one). English shares many words, ideas, concepts and constructs as languages such as Spanish, French and Italian.
Spanish, French, Italian and other languages evolved from Proto-Italic are relatively easy for native English speakers to learn because the languages are similar. However, languages such as Russian that evolved from the Proto-Slavic family are generally harder to learn.
Coming from such different regions as Italy and Northern Europe, How similar were Proto-Italic and Proto-Germanic, and why are their descendant languages so mutually easy to learn compared to other Proto-Indo-European descended languages?