It kind of depends on what you want to do.
Like Zia said, the St. Paul Center’s online study is great.
I like the Ignatius Catholic Study Bible, which comes in paperback volumes that study one or two books at a time. They have the Bible text, with commentary below. They’re thin books, so if you drop them on Baby, it won’t hurt.

The commentary is pretty easy to understand. They’re on good quality paper, so they don’t suffer too much from getting wet. They also have study questions.
It’s not complete yet; they’ve only done the NT so far, but haven’t gotten to 1, 2, &3 John and Revelations - as far as I know. Ignatius doesn’t list them yet, anyway. The OT is probably even further off.
You can buy them as a set, or one at a time. They’re about $10 per volume.
More basic, and less involved is Inside the Bible by Fr. Kenneth Baker, S.J. It gives overviews of each book of the Bible that are pretty good. It’s also from Ignatius Press. I can’t remember what I paid for mine - a well-bound paperback. Since it doesn’t also have the Bible text, you’ll have to juggle books.
The Navarre Bible comes in big hardback volumes, with Bible text and commentary like the Ignatius ones. It’s also good, but less convenient. It does cover the whole Bible.
This is also a good one. Its format would make it pretty tempting for a toddler to investigate, though! Bright colors and stuff.
This one’s far from basic, but I’ll tell you anyway! If you are in or near the Denver Archdiocese, investigate the Denver Catholic Biblical School. It’s a four year course, very intensive. You’d need a fair amount of both time and money. But it’s great!
All of the above are Catholic, of course.
God bless you,
Ruthie