Modern Hebrew is indeed about a century old. But a huge proportion of its vocabulary and grammar and based on the Bible, and many centuries of Jewish religious and legal writing. Don't forget that for 2,000 years, Jews have prayed, studied, written, and communicated in Hebrew.
It's easier for a native Hebrew speaker to read the Bible or rabbinic literature than for a native English speaker to read Shakespeare. Moreover, a good grounding in Biblical and rabbinic Hebrew grammar and vocabulary makes modern Hebrew far easier to understand.
To say that modern Hebrew is "made up" exaggerates the degree to which Hebrew exists on a continuum. It was revived as a spoken, day-to-day language used for non-religious, non-legal affairs. But there are more than 2,000 years of Hebrew documents out there, and they contribute massively to everything from idioms to grammar to vocabulary -- along with many modern terms from English, Russian, French, Arabic, and other languages.
It's easier for a native Hebrew speaker to read the Bible or rabbinic literature than for a native English speaker to read Shakespeare. Moreover, a good grounding in Biblical and rabbinic Hebrew grammar and vocabulary makes modern Hebrew far easier to understand.
To say that modern Hebrew is "made up" exaggerates the degree to which Hebrew exists on a continuum. It was revived as a spoken, day-to-day language used for non-religious, non-legal affairs. But there are more than 2,000 years of Hebrew documents out there, and they contribute massively to everything from idioms to grammar to vocabulary -- along with many modern terms from English, Russian, French, Arabic, and other languages.