You do not need to learn Hadoop to be a Data Scientist. There is this false public perception that data science is always about very large data sets. Data scientists work on data of any size. The research skills are that separates a data scientist from a Data Engineer or Machine Learning Engineer.
If you are looking for an online course to learn Data Science, then check out this Data Science Online Course by Intellipaat.
Also, watch this video on Data Science for beginners to understand more: