Currently active Kaggle Competitions are always available here: https://www.kaggle.com/competitions, but competitions which have since closed are still open for late submissions without as much competitive pressure. This is a shortlist of ones we brainstormed which you might consider. There are a number of our Getting Started competitions that cover classic datasets & problem use cases, often with introductory starter materials.
Topics/ Skills to Learn: Classic Introductory Simple Tabular Prediction
Level: Novice State: Getting Started
Topics/ Skills to Learn: Sales Forecasting
Level: Novice State: Getting Started
Topics/ Skills to Learn: Classic Computer Vision/Image Classification Problem & Dataset
Level: Novice, Intermediate State: Getting Started
Topics/ Skills to Learn: Computer Vision Binary Image Classification
Level: Novice State: Playground
Topics/ Skills to Learn: Natural Language Processing
Level: Novice, Intermediate State: Playground
Topics/ Skills to Learn: Natural Language Processing
Level: Novice, Intermediate State: Playground