Now, this is not taking into account slang, only formal, official languages. How far could Latin, or Germanic languages like English, Spanish, French and German take me? Would Asian languages such as Japanese, Chinese or Hindi be able to take me back further?
Also for bonus points, which dead language could I learn well enough today to allow me to survive in the past, ancient Greek, Latin, Sumerian?
Concerning Spanish, I answered a similar question two years ago. You could understand, and be understood, at least in the XVI century, although people would mention you have an odd accent.
https://www.reddit.com/r/AskHistorians/comments/7x4dyy/could_a_modern_day_spanish_speaker_have_a/
This question is asked vis-à-vis the English language quite frequently.
This comment by /u/knoperope in a previous ask contains a wealth of links if you're interested in going down the rabbit hole, but I recommend using the search bar to find quite a few very solid, verified, answers.
Concerning Hebrew, you may be able to travel back as far as the 10th century BCE. However, Biblical Hebrew (which is what was spoken then), and Modern Hebrew are still very different. A speaker of Modern Hebrew can probably understand more or less what a speaker of Biblical Hebrew is saying, but there are still many differences, both in grammar and vocabulary. Hebrew may be the 'oldest' language that a time traveller could understand, because it was a dead language that stopped evolving for hundreds or years.
As with any language, language change is something that constantly evolves and shifts. Looking at this from a more general, historical linguistic perspective, I would estimate that on average you will be able to travel back between 200 and 300 years and still be able to understand a language, but even then it will be very difficult and confusing. The structure is likely to be very similar, but there will be many words that you think you know, but that have undergone significant semantic change. A great example is the following paragraph by John Algeo that is given in many linguistics text books:
He was a happy and sad girl who lived in a town 40 miles from the closest neighbour. His unmarried sister, a wife who was a vegetarian member of the Women's Christian Temperance Union, ate meat and drank liquor three times a day. She was so fond of eating that one night she starved from overeating. The brother liked to feed nuts to the deer that lived in the branches of an apple tree that bore pears. He was a silly villain*, whom everybody liked.*
The bold words have undergone semantic change; sad = satisfied; girl = child of either gender; town = yard, court; wife = woman; meat = meal, food; liquor = beverage; starved = died; deer= animal; apple = fruit; silly = blessed; villain = village person.