There is scope here for making as well as buying. Plastic beakers that will build up or fit inside each other as well as being used in the bath are a cheap and easy version of many stacking toys. She will probably also like a first jigsaw where whole figures lift out by a knob. Soon she'll be ready to tackle standard jigsaws with a few large pieces. Your toddler may hook a plastic quoit with your umbrella or experiment with a train with simple couplings.
Closed rings are fun to thread on anything long and thinner.
Eventually she will enjoy threading curtain rings or cotton reels onto a piece of wool or a shoelace. She needs lots of interesting objects, varied containers and patience from caring adults. Grouping things with her hands helps her do it with her brain. Later still, you may see her considering universal dilemmas, such as whether the apple goes with the ball because they are both round, or with the biscuit because they are both edible. They must be well-made, though, so that once she discovers how two objects fit together, they do actually fit.