The Arabic version of the Quran is the best as it's the language of the original revelation but translation is a necessity due to the majority of Muslims being non-Arabic speakers so that they can easily recite and understand the Quran.
Yes, you need to learn Arabic to understand Quran. Quran has hundreds of translations that may assist people who don't speak Arabic to understand what's written in it. However, these translations are not enough to capture the beauty of the Quran and its accurate meanings. Allah SWT said:I'm telling you as an experienced Quranic Arabic teacher, having now taught hundreds of non-Arabs, that learning Arabic, understanding the Quran and being able to speak Arabic is easy. Allah, the Glorious, the Majestic tells all of us that He is the One who has made this Quran easy for all.U1EAKj.