Writing the syntax by hand
A Markdown table is pipes between cells and a dashed rule under the header. That is easy for three columns and tedious for eight, and the tedium is where the mistakes come from: one missing pipe and the whole row renders as text.
Alignment is set by putting colons in the rule. A colon on the left is left-aligned, on the right is right-aligned, on both is centred. The control here writes them so you do not have to remember which is which.
What Markdown tables cannot do
No merged cells, no nested tables, no multi-line cells. A row ends at the newline, so a value that needs a line break uses a <br> tag, which every common renderer passes through.
Tables are not in the original Markdown specification at all. They come from GitHub Flavored Markdown, which is why they work on GitHub, GitLab, Obsidian and most static site generators, and not in every renderer that calls itself Markdown.